The herbal supplement ginkgo biloba does not slow cognitive decline, a study published Tuesday in the Journal of the American Medical Association (JAMA) said.
Researchers from the University of Pittsburgh analyzed data in an eight-year randomized, double-blind placebo-controlled trial called the Ginkgo Evaluation of Memory (GEM) study, for which half of the 3,069 participants were given daily doses of ginkgo biloba and the other half were given a placebo.
"In the United States and particularly in Europe, ginkgo biloba is perhaps the most widely used herbal treatment consumed specifically to prevent age-related cognitive decline," the report of their findings in JAMA said.
"We found no evidence for an effect of G biloba on global cognitive change and no evidence of effect on specific cognitive domains of memory, visual-spatial construction, language, attention and psychomotor speed, and executive functions," the study said.
The results confirm those of earlier, but smaller, tests and follow on from an earlier finding of the GEM study that taking ginkgo does not reduce the incidence of Alzheimer's dementia or other dementia.
In the GEM study, participants aged 72-96 years with little or no cognitive impairment were recruited from four communities in the eastern United States and received either a twice-daily dose of 120-milligrams of extract of G biloba or an identical-looking placebo.
Changes in cognition were assessed by various tests given during the study, which was conducted at six academic medical centers in the United States between 2000 and 2008.
A US resident would spend a minimum of 12 dollars a month to take 240 milligrams daily of ginkgo biloba, with some brands of the herbal supplement costing around twice as much.
The news wasn't all bad for ginkgo takers, though. The JAMA report said that ginkgo biloba "may have prevented or delayed age-related changes in individuals with normal cognition ... or slowed the rate of decline in those characterized as having mild cognitive impairment."